Professor Marcio J. T. da Costa

@workingpaper{cardias2025edgenoncollinearmagnetismnanoribbons,

title = {Edge non-collinear magnetism in nanoribbons of Fe3GeTe2 and Fe3GaTe2},

author = {R. Cardias and Anders Bergman and Hugo U. R. Strand and R. B. Muniz and Marcio Costa},

url = {https://arxiv.org/abs/2502.12356},

year  = {2025},

date = {2025-02-17},

urldate = {2025-01-01},

abstract = {Fe3GeTe2 and Fe3GaTe2 are ferromagnetic conducting materials of van der Waals-type with unique magnetic properties that are highly promising for the development of new spintronic, orbitronic and magnonic devices. Even in the form of two-dimensional-like ultrathin films, they exhibit relatively high Curie temperature, magnetic anisotropy perpendicular to the atomic planes and multiple types of Hall effects. We explore nanoribbons made from single layers of these materials and show that they display non-collinear magnetic ordering at their edges. This magnetic inhomogeneity allows angular momentum currents to generate magnetic torques at the sample edges, regardless of their polarization direction, significantly enhancing the effectiveness of magnetization manipulation in these systems. We also demonstrate that it is possible to rapidly reverse the magnetization direction of these nanostructures by means of spin-orbit and spin-transfer torques with rather low current densities, making them quite propitious for non-volatile magnetic memory units.},

keywords = {},

pubstate = {published},

tppubtype = {workingpaper}

}

@workingpaper{cysne2025orbitronicstwodimensionalmaterials,

title = {Orbitronics in Two-dimensional Materials},

author = {Tarik P. Cysne and Luis M. Canonico and Marcio Costa and R. B. Muniz and Tatiana G. Rappoport},

url = {https://arxiv.org/abs/2502.12339},

year  = {2025},

date = {2025-02-17},

urldate = {2025-01-01},

abstract = {Orbitronics explores the control and manipulation of electronic orbital angular momentum in solid-state systems, opening new pathways for information processing and storage. One significant advantage of orbitronics over spintronics is that it does not rely on spin-orbit coupling, thereby broadening the range of non-magnetic materials that can be utilized for these applications. It also introduces new topological features related to electronic orbital angular momentum, and clarifies some long-standing challenges in understanding experiments that rely on the conventional concept of valley transport. This review highlights recent advances in orbitronics, particularly in relation to two-dimensional materials. We examine the fundamental principles underlying the generation, transport, and dynamics of orbital angular momentum to illustrate how the unique properties of two-dimensional materials can promote orbitronic phenomena. We also outline potential future research directions and address some outstanding questions in this field.},

keywords = {},

pubstate = {published},

tppubtype = {workingpaper}

}

@workingpaper{Dugato2024,

title = {Curved Nanomagnets: An Experimental Archetype for Skyrmion Stabilization},

author = {Danian A. Dugato and Wesley Jalil and Ramon Cardias and Marcelo Albuquerque and Marcio Costa and Flavio Garcia},

url = {https://www.researchsquare.com/article/rs-4547588/v1},

doi = {10.21203/rs.3.rs-4547588/v1},

year  = {2024},

date = {2024-06-10},

urldate = {2024-06-10},

publisher = {Research Square Platform LLC},

abstract = {In the fields of nanomagnetism and spintronics, the controlled stabilization of mag- netic skyrmions is a topic of great interest for potential applications in data storage and innovative computing systems. This study delves into the intriguing phenomenon of skyrmions on a hexagonal array of curved nanomagnets. Through a combination of atomistic calculation, micromagnetic simulations, and experimental observations, we thoroughly explore the intricate interplay between magnetic parameters, curvature, and interfacial Dzyaloshinskii-Moriya interaction (iDMI) in the formation of these topolog- ically non-trivial magnetic structures. We have observed the spontaneous formation of isolated skyrmions (<150 nm) on a curved nanomagnet matrix of symmetric Pt/Co/Pt multilayer without the necessity of applied fields. Our research sheds light on the pro- found impact of geometric curvature on iDMI, offering invaluable insights for engi- neering and controlling skyrmionic configurations. This work advances nanomagnetism knowledge and sets the stage for designing skyrmion-based technologies.},

howpublished = {Research Square},

keywords = {},

pubstate = {published},

tppubtype = {workingpaper}

}

@workingpaper{cysne2023ultrathin,

title = {Ultrathin films of black phosphorus as suitable platforms for unambiguous observation of the orbital Hall effect},

author = {Tarik P. Cysne and Marcio Costa and Marco Buongiorno Nardelli and R. B. Muniz and Tatiana G. Rappoport},

url = {https://arxiv.org/abs/2307.03866},

doi = {10.48550/arXiv.2307.03866},

year  = {2023},

date = {2023-01-01},

urldate = {2023-01-01},

abstract = {Phosphorene, a monolayer of black phosphorus, is a two-dimensional material that lacks a multivalley structure in the Brillouin zone and has negligible spin-orbit coupling. This makes it a promising candidate for investigating the orbital Hall effect independently of the valley or spin Hall effects. To model phosphorene, we utilized a DFT-derived tight-binding Hamiltonian, which is constructed with the pseudo atomic orbital projection method. For that purpose, we use the PAOFLOW code with a newly implemented internal basis that provides a fairly good description of the phosphorene conduction bands. By employing linear response theory, we show that phosphorene exhibits a sizable orbital Hall effect with strong anisotropy in the orbital Hall conductivity for the out-of-plane orbital angular momentum component. The magnitude and sign of the conductivity depend upon the in-plane direction of the applied electric field. These distinctive features enable the observation of the orbital Hall effect in this material unambiguously. The effects of strain and of a perpendicularly applied electric field on the phosphorene orbital-Hall response are also explored. We show that a supplementary electric field applied perpendicular to the phosphorene layer in its conductive regime gives rise to an induced in-plane orbital magnetization.},

keywords = {},

pubstate = {published},

tppubtype = {workingpaper}

}